Molding is a process by virtue of which a molded article can be formed from molding material by using a molding system. Various molded articles can be formed by using the molding process, such as an injection molding process. One example of a molded article that can be formed, for example, from polyethelene terephalate (PET) material is a preform that is capable of being subsequently blown into a beverage container, such as, a bottle and the like.
As an illustration, injection molding of PET material involves heating the PET material (ex. PET pellets, PEN powder, PLA, etc.) to a homogeneous molten state and injecting, under pressure, the so-melted PET material into a molding cavity defined, at least in part, by a female cavity piece and a male core piece mounted respectively on a cavity plate and a core plate of the mold. The cavity plate and the core plate are urged together and are held together by clamp force, the clamp force being sufficient enough to keep the cavity and the core pieces together against the pressure of the injected PET material. The molding cavity has a shape that substantially corresponds to a final cold-state shape of the molded article to be molded. The so-injected PET material is then cooled to a temperature sufficient to enable ejection of the so-formed molded article from the mold. When cooled, the molded article shrinks inside of the molding cavity and, as such, when the cavity and core plates are urged apart, the molded article tends to remain associated with the core piece. Accordingly, by urging the core plate away from the cavity plate, the molded article can be demolded, i.e. ejected off of the core piece. Ejection structures are known to assist in removing the molded articles from the core halves. Examples of the ejection structures include stripper plates, ejector pins, etc.
Depending on a type of the finished molded article, the quality is more or less critical. However, it can be generally said that quality of the finished molded article is paramount for a number of reasons. With some applications, the quality is more an issue of aesthetics and customer appeal, with other applications, quality is essential for proper functioning of the molded article and/or subsequent handling thereof (such as, for example, blow molding of a preform into a beverage container). Quality of the finished molded articles depends on many parameters, one of which includes content of moisture in the ambient air in substantially close proximity of a molding machine. Presence of the ambient moisture within the molding machine can lead to a number of operational problems and quality defects. Examples of such operational problems and quality defects include, but are not limited to, problems associated with transferring molded articles out of cooling receptacles (ex. cooling tubes), marks on the molded articles, etc. This problem is particularly exacerbated when the molding machine is operated in a location with a relatively high humidity levels.
It has been known to use a dehumidifier to remove dewing from the molding system. An example of such an arrangement is disclosed in a Japanese patent application bearing a publication number 2000202895A (Inventors: Nishizawa Toshio, Ogiwara Shuichi; Publication date: Jul. 25, 2000). This patent application teaches an air conditioner 62 of an injection stretch blow molding machine. The injection stretch blow molding machine has an injection molding station, where a molten synthetic resin into is injected into a cooled mold to mold to form a preform. There is also provided a blow molding station 16, where the injection-molded preform is heated to a proper blow molding temperature to subject the same to stretch blow molding. The respective molding work space atmospheres of the injection molding station 14 and the blow molding station 16 are isolated by an isolating sheet 64 and the isolated injection molding station is dehumidified by a dehumidifier 66.
U.S. Pat. No. 4,976,900 issued to Tsutsumi on Dec. 11, 1990 discloses a method and an apparatus for injecting a steam into a mold in an injection molding machine by injecting a desired stream toward the opening of the metal mold including a gate and cavities in connection with the opening and closing operation of the metal mold thereby intending the cooling solidification of the molten resin on the gate portion and simultaneously intending removal of dewing and an oily matter on the surface of the metal mold.
U.S. Pat. No. 7,168,942 issued to Wieder on Jan. 30, 2007 discloses a method and apparatus for controlling the temperature of an injection mold by passing pressurized air contained in an air supply tube through an orifice into an exhaust channel, wherein the pressure of the air in the exhaust channel is lower than the pressure of the air in the air supply tube. As the pressurized air is released through the orifice, cooling is produced that can be applied to a portion of an injection mold where cooling is desired, in order to control the temperature of that portion of the injection mold.
European patent application bearing a publication number 0122885B1 (Inventors: Piazzola, Gaetano; Publication date: Nov. 15, 1989) discloses a system for extruding, drawing, vacuum molding or processing, or the like hot processing of plastomers or elastomers, which can conveniently utilize the hot air from the cooling process of its heated component parts. The system makes use, to heat the extruder cylinder, of ventilated electric thermal units 1 wherein ventilation is performed in closed circuit fashion. In particular, arrangements are made to convey the hot air from the cited electric thermal unit 1, through specially provided ducting 5, 6, 7, to areas of the system where application of heat is required.
U.S. Pat. No. 5,714,109 issued to Diller on Feb. 3, 1998 discloses a method and apparatus which allows blow-molded plastic containers to be manufactured at high rates of production independent of ambient environmental conditions. The method and apparatus eliminate the need to make adjustments to blow-molding oven operating parameters when environmental conditions change and reduce defects such as caused by water spots. The method includes the steps of flowing ambient air over cooling coils to remove moisture, heating the air to a constant pre-determined temperature and delivering the conditioned air to the blow-molding oven. The apparatus includes a variable speed blower which forces ambient air at a predetermined volumetric flow rate over cooling coils and an electric heater to provide the blow molding oven with a constant volumetric flow rate of constant temperature and low humidity air.
British patent 2 064 099 (Inventor: Stuart Lawson; Publication date: Jun. 10, 1981) discloses a conventional refrigeration-type dehumidifier that has an air cooler such as an evaporator for cooling the air in order to condense the required amount of moisture, followed by a heater to heat the airstream to the required temperature. An air-to-air heat exchange system is provided which transfers hear from the airstream before the air cooler to the stream after the air cooler.